Diabetes Treatment (cont.)

Robert Ferry Jr., MD

Robert Ferry Jr., MD, is a U.S. board-certified Pediatric Endocrinologist. After taking his baccalaureate degree from Yale College, receiving his doctoral degree and residency training in pediatrics at University of Texas Health Science Center at San Antonio (UTHSCSA), he completed fellowship training in pediatric endocrinology at The Children's Hospital of Philadelphia.

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Different methods of delivering insulin

Not only is the variety of insulin preparations growing, so are the methods
for administering insulin.

Pre-filled insulin pens

In the twentieth century, insulin was available only in an injectable form
that required carrying syringes (which were made of glass and required
sterilization just a few decades ago), needles, vials of insulin, and alcohol
swabs. Clearly, patients found it difficult to take multiple shots each day; as
a result, good blood sugar control was often compromised. Many pharmaceutical
companies now offer discreet and convenient methods for delivering insulin.

Many manufacturers offer pen delivery systems. Such systems resemble the ink
cartridge in a fountain pen. A small, pen-sized device holds an insulin
cartridge (usually containing 300 units). Cartridges are available for the most
widely used insulin formulations. The amount of insulin to be injected is dialed
in, by turning the bottom of the pen until the required number of units is seen
in the dose-viewing window. The tip of the pen consists of a needle that is
replaced with each injection. A release mechanism allows the needle to penetrate
just under the skin and deliver the required amount of insulin. The cartridges
and needles are disposed of when finished and new ones simply are inserted. In
some systems, the entire pen is disposed. These insulin delivery devices are
less cumbersome than traditional methods.

Insulin pumps

Over the past 20 years, dramatic advances in insulin delivery have improved
insulin pumps. An insulin pump is composed of a reservoir similar to that of an
insulin cartridge, a battery-operated pump, and a computer chip that allows the
user to control the exact amount of insulin being delivered. Current pumps on
the market are about the size of a pager or beeper. The pump is attached to a
thin plastic tube (an infusion set) that has a cannula (like a needle but soft)
at the end through which insulin passes. This cannula is inserted under the
skin, usually on the abdomen. The cannula is changed every two days. The tubing
can be disconnected from the pump while showering or swimming. The pump
continuously delivers insulin, 24 hours a day. The amount of insulin is
programmed and is administered at a constant rate (basal rate). Often, the
amount of insulin needed over the course of 24 hours varies, depending on
factors like exercise, activity level, and sleep. The insulin pump allows the
user to program many different basal rates to allow for variations in lifestyle.
The user can also program the pump to deliver additional insulin during meals,
covering the excess demands for insulin caused by eating carbohydrates.

Insulin pumps enable tight blood sugar control and support lifestyle
flexibility, while minimizing the effects of low blood sugar (hypoglycemia). At
present, the pump is the closest device on the market to an artificial pancreas.
The latest pumps do not require tubing. The insulin delivery device is placed
directly on the skin and any adjustments needed for insulin delivery are made
through a PDA-like device that must be kept within a 6-foot range of the
insulin delivery device (and can be worn in a pocket, kept in a purse, or on a
tabletop when working).

The most exciting innovation in pump technology has been the ability to
combine the pump in tandem with newer glucose sensing technology. Glucose
sensors have improved dramatically in the last few years and are an option for
patients to gain further insight into their patterns of glucose response to
tailor a more individual treatment regimen. The newest generation of sensors
allows for a real-time glucose value to be given to the patient. The implantable
sensor communicates wirelessly with a pager-sized device that has a screen. The
device is kept in proximity to the sensor to allow for transfer of data;
however, it can be a few feet away and still receive transmitted information.
Depending on the model, the screen displays the blood glucose reading, a thread
of readings over time, and a potential rate of change in the glucose values.
Sensors can be programmed to produce a "beep" if blood sugars are in a range
that is selected as too high or too low. Some can provide a warning beep if the
drop in blood sugar is occurring too quickly.

To take things one step further, there is one particular sensor that is new
to the market that is designed to communicate directly with the insulin pump.
While the pump does not yet respond directly to information from the sensor, it
"requests" a response from the patient if there is a need for adjustments
according to the patterns it has been programmed to detect. The ultimate goal of
this technology is to "close the loop" by continuously sensing what the body
needs, then responding with the appropriate insulin dose.

Inhaled insulin

Inhaled insulin was approved by the FDA and marketed by Pfizer in 2006 as
Exubera. Exubera was poorly accepted after marketing and was subsequently
discontinued during October 2007.

Intranasal or transdermal insulin

Other routes for the delivery of insulin have been tried. Intranasal insulin
delivery was initially promising; however, this approach was associated with
poor absorption and nasal irritation. Transdermal insulin delivery (via skin
patch) yielded disappointing results. Insulin in pill form is ineffective since
digestive enzymes in the gut break it down. Surprisingly, oral insulin is being
tested in a major clinical trial by TrialNet as a potential intervention to
prevent type 1 diabetes in those at high risk of progressing from to overt type
1 diabetes.